mpg experiment in a 120d auto ED

[carlovers]

went down the m4 in the above 5 month old car. For 10 miles tried to keep at 80mph on the opc average was 47mpg. Another 10 miles at 70 gave me 55mpg av. Then for 15 miles between 55 and 60 being as gentle as i could i got 72 mpg which i thought was amazing. I have got a dieselpower tuning box on which apparently gives around 7% saving .

[raysingh]

I did this the other week in my newly acquired e46 320d auto:

1. Drove nun-like LHR to Cardiff = 47mpg
2. Return trip as if it were my last tank of diesel (& laden with two sets of rims & tyres) = 45mpg

My conclusion - cane it wherenever possible

[jlanng]

How do the MPG improvements on these tuning boxes work? Better atomisation through higher pressures?

I'm sceptical - surely it's just fooling the car's computer.

[cptsideways]

jlanng said:

How do the MPG improvements on these tuning boxes work? Better atomisation through higher pressures?

I'm sceptical - surely it's just fooling the car's computer.

They usually advance the timing of the injection pulses, slightly higher EGT's as a result but rarely harmfull.

[andye30m3]

raysingh said:

I did this the other week in my newly acquired e46 320d auto:

1. Drove nun-like LHR to Cardiff = 47mpg
2. Return trip as if it were my last tank of diesel (& laden with two sets of rims & tyres) = 45mpg

My conclusion - cane it wherenever possible

47mpg from a 2 litre diesel doesn't sound great, I did a 15mile trip driving as easy as possible and averaged 40.4 in my E36 M3 Evo.